Many women, from the age of thirty five, and more particularly after menopause, frequently complain of drying out of their skin, and of the manifestations of discomfort or unaesthetic manifestations which result therefrom (desquamation, dull complexion, atonia of the skin). Now, this drying out is due, as is now known, to a decrease in the production of sebum with age.
Moreover, children in whom the sebaceous function is not yet active often exhibit signs of dry skin.
Sebum is the natural product of the sebaceous gland which, along with the sweat produced by the eccrine or aprocrine glands, constitutes a natural moisturizer for the epidermis. It consists essentially of a more or less complex mixture of lipids. Conventionally, the sebaceous gland produces squalene, triglycerides, aliphatic waxes, cholesterol waxes and possibly free cholesterol (Stewart, M. E., Semin. Dermatol. 11, 100–105 (1992)). The action of bacterial lipases converts a varying portion of the triglycerides to free fatty acids.
The sebocyte constitutes the competent cell of the sebaceous gland. The production of sebum is associated with the programme of terminal differentiation of this cell. During this differentiation, the metabolic activity of the sebocyte is essentially centred around the biosynthesis of lipids (lipogenesis), and more precisely around the neosynthesis of fatty acids and the squalene.
A compound making it possible to stimulate the production of the lipids constituting sebum, by the cells of the sebaceous gland (sebocytes), would therefore be of definite value for the treatment of oligoseborrheic dry skin, i.e. skin exhibiting a sebum content of less than 100 μg/cm2 on the forehead.
For this purpose, in patent U.S. Pat. No. 4,496,556, the use of DHEA, a steroid secreted by the adrenal glands, or esters thereof, administered topically, has been proposed in order to increase the production of sebum.
However, for regulatory reasons, it is not always possible to use this type of compound in the cosmetics field. In addition, it is not sufficiently effective on oligoseborrheic skin. There remains therefore the need to have cosmetically acceptable compounds which make it possible to effectively stimulate the sebaceous function for the purpose of treating oligoseborrheic dry skin.